WTC7 and the girder walk-off between column 79 and 44

[NoahFence]

It is a shame you haven't been able to prove that to me. I actually wish you could.

I think I found your problem....

 

[Senenmut]

No it isn't that easy. Ozeco, and anyone who agrees with him, needs to provide the actual mechanisms for what he is claiming. Just saying the whole building was swaying or was on fire and that this produced forces and mechanics supporting what you are saying is farcical. You can give rough estimates but you need to be specific about how certain forces would have developed and the mechanics that would have been involved to cause column to column relationship changes.

do you think there is any way to get the data from their "surveying instruments"?? i wonder what it would show? maybe from a foia but how would i go about that considering its the fire dept that made the measurements.
Peter Hayden:
“We had our special operations people set up surveying instruments to monitor, and see if there was any movement of, [WTC 7]. We were concerned of the possibility of collapse of the building. And we had a discussion with one particular engineer there, and we asked him, if we allowed it to burn could we anticipate a collapse, and if so, how soon?” The engineer apparently predicts correctly that WTC 7 will collapse and also the time it will take before it comes down. As Hayden will continue: “And it turned out that he was pretty much right on the money, that he said, ‘In its current state, you have about five hours.’” Hayden will not reveal the name of this engineer.

 

[carlitos]

Please learn to provide links to your quoted material and use the quote function.

 

[Senenmut]

Please learn to provide links to your quoted material and use the quote function.

http://www.youtube.com/watch?v=jeYPm8XzC3g

start at 19:30

 

[tfk]

Ozeco, you have yet to provide one iota of a basis for your claim that the relationship between columns 44 and 79 could have been changed and have no business saying my assumption here has been shown to be improper or incorrect.

NIST didn't bring up anything in this regard, and they did a finite element model and fire simulation of the entire building. If something had happened, like what you are wildly postulating, that would have helped their case for collapse due to fire, they would have.

Tony,

You are wrong.

And I've got the NIST quotes to prove it.

On Floors 10, 11, and 12 (Figure 11–32, Figure 11–33, and Figure 11–34), the girder between Columns 76 and 79 failed due to a tensile weld failure in the knife connection on the west side of Column 79. Temperatures in this region were less than 100 °C on these floors. The tensile force in the connection was due to an eastward lateral displacement of Column 79, which was primarily caused by thermal expansion of the girder between Column 76 and Column 79 at Floor 13.

NCSTAR1-9 vol 2, pg 504, pdf pg 166.

NIST did, in fact, say explicitly that col 79 was pushed eastward. They explicitly say that the force required to push it eastward had to be small. That is, less than the force to shear the 2 construction bolts, as proven by the 0% failure in these connection bolts (on the west side of col 79 on floor 13) as shown in Fig. 11-35 of NCSTAR1-9 v2, pg. 511.

Which makes the lateral stiffness of the columns far less than you have been portraying it.

And it is simple to understand why: The AXIAL stiffness of the columns is proportional to the cross-sectional area of the column, because the columns rested on their milled, mating surfaces. But the LATERAL stiffness is not proportional to the columns cross sectional area (or MOI), because the column segments are not welded to each other.

Instead, the segments (at every 2nd story) are joined by two 14" wide x 5/8" thick column splice plates (one on the north side of C79 and one on the south side). But the only real connection between the columns passes thru one 14" long x 0.5" fillet weld and two 8" x 0.5" fillet welds on each splice plate, as shown on dwg 1091.

Although not shown, it is probable that there are symmetric welds where these plates mate to the column above the one shown.

This design makes these joints incredibly weak when loaded from the side.

To SIDE loads, it wouldn't matter if the column webs and build-up plates had been twice as thick as they were, or if the splice plates were twice as thick. The lateral stiffness of the columns was limited by the (low) strength of these fillet welds.

The low lateral stiffness also means that col 79 will have expanded approximately the entire amount of the unconstrained thermal expansion of the girder between col 76 & col 79. Which is a total of about 5".

THERE is your walk-off, Tony.

6" westward push of the girder and ~5" eastward push of the column & seat produces about 11" of total relative motion between the girder end & the seat. More than enough for a walk-off.

And all of this drops right out of the competent FEA that NIST performed. And all of the details are contained within the NIST report, even tho the exact components of the motion are not explicitly noted.

I'll await your reply.

Or lack of one.


tk

 

[carlitos]

Hayden will not reveal the name of this engineer.

The above claim is not found at the video you linked. Please correct me if I'm wrong, or provide a source for the assertion.

 

[tfk]

No it isn't that easy. Ozeco, and anyone who agrees with him, needs to provide the actual mechanisms for what he is claiming. Just saying the whole building was swaying or was on fire and that this produced forces and mechanics supporting what you are saying is farcical. You can give rough estimates but you need to be specific about how certain forces would have developed and the mechanics that would have been involved to cause column to column relationship changes.

Wrong.

It is exactly that easy.

It is trivially easy to assert, with 100% assurance, that any tall structure built with a latticework of support columns, that starts to lean, and whose RATE of leaning does not return to zero, will collapse.

[And, yes, this includes a tower in the town of Pisa.]

And it is possible to assert this unequivocally, without knowing anything about the structure's assembly details.

WTC7 was leaning, as measured by the FDNY's transit measurements. It's rate of lean never returned to zero throughout the afternoon.

It was doomed by this.

 

[Tony Szamboti]

Tony,

You are wrong.

And I've got the NIST quotes to prove it.



NCSTAR1-9 vol 2, pg 504, pdf pg 166.

NIST did, in fact, say explicitly that col 79 was pushed eastward. They explicitly say that the force required to push it eastward had to be small. That is, less than the force to shear the 2 construction bolts, as proven by the 0% failure in these connection bolts (on the west side of col 79 on floor 13) as shown in Fig. 11-35 of NCSTAR1-9 v2, pg. 511.

Which makes the lateral stiffness of the columns far less than you have been portraying it.

And it is simple to understand why: The AXIAL stiffness of the columns is proportional to the cross-sectional area of the column, because the columns rested on their milled, mating surfaces. But the LATERAL stiffness is not proportional to the columns cross sectional area (or MOI), because the column segments are not welded to each other.

Instead, the segments (at every 2nd story) are joined by two 14" wide x 5/8" thick column splice plates (one on the north side of C79 and one on the south side). But the only real connection between the columns passes thru one 14" long x 0.5" fillet weld and two 8" x 0.5" fillet welds on each splice plate, as shown on dwg 1091.

Although not shown, it is probable that there are symmetric welds where these plates mate to the column above the one shown.

This design makes these joints incredibly weak when loaded from the side.

To SIDE loads, it wouldn't matter if the column plates were twice as thick as they were, or if the splice plates were twice as thick. The lateral stiffness of the columns was limited by the (low) strength of these fillet welds.

All of this also means that col 79 will have expanded the entire amount of the unconstrained thermal expansion of the girder between col 76 & col 79. Which is a total of about 5".

THERE is your walk-off, Tony.

6" westward push of the girder and ~5" eastward push of the column & seat produces about 11" of total relative motion between the girder end & the seat. More than enough for a walk-off.

And all of this drops right out of the competent FEA that NIST performed. And all of the details are contained within the NIST report, even tho the exact components of the motion are not explicitly noted.

I'll await your reply.

Or lack of one.


tk

First, NIST has not shown us FEA results of the situation you mention here. They only make the claim that the girder at floor 13 caused the west side girder knife connections at floors 10, 11 and 12 to fail.

Second, they don't include the flange stiffeners on the girder or the plate below the girder seat (that we now know were there due to drawings #9114 and 1091 being released) in the FEA you are capriciously calling competent.

Third, the splice plates were much thicker and had many more bolts than you say and they are designed to maintain the column's MOI. If you want to dispute that you need to provide references and show calculations.

Fourth, NIST does not imply that the push from the girder at the floor above helped in the walk-off of the girder at the ceiling of the 12 th floor between columns 79 and 44. That is pure TFK talk there.

The west side girders had twelve beams connected to them orthogonally, six from the north and six from the south, with shear studs in their slabs. Unless these beam to girder connections are broken that girder isn't deflecting column 79 anywhere. If the beam to girder connections are broken the west side girder is a slender 45 foot long W33 x 130 beam which would buckle with a 213,000 lb force applied to it at room temperature and a lot less at the temperatures you need for expansion. This force would deflect column 79 less than 0.100" at the floor below where they say the girder walk-off its seat. So no, this doesn't help your walk-off at all.
.
When you show how much force the girder would have to apply to column 79 for the displacement you claim and how the girder would be able to do that without buckling then we can talk.

The NIST claim for the girder at floor 13 breaking the connections of the west side girders of column 79 at floors 10, 11 and 12 is specious and it is no wonder they don't show FEA results to support this claim.

The NIST claim for walk-off of the girder between columns 79 and 44 has been shown to be impossible and the attempted apologetics by people like yourself and Ozeco have no merit.

 

[tfk]

I have already shown on this thread that column 79 could not have been pushed to the east any significant amount by its girders, since they would buckle before being able to do so. Column 44 was on the exterior and being cooled with a large moment frame keeping it in place.

The only thing that you've shown is your incompetence with mechanical analysis.

You ignore critical features, as in "the effect of column joint design on the lateral stiffness of the columns".

Then you produce analyses that are massively flawed.

Supported by the most brain-dead, idiotic political agenda I've ever had the annoyance to witness. Such as:

"they demo'd an internal column to make sure the EPH didn't 'fly off' the top of the building, or cause the building to topple". [As if the terrorists of 9/11 were the slightest bit concerned about minimizing collateral damage, instead of maximizing it.]

... and ...

"The FFs knew the building was going to collapse. They couldn't have known that unless the CDers told them so." [As if someone engaged in such a massive, treasonous conspiracy is going to tell a bunch of people about it as it is happening.]

Absolutely brain-dead.

 

[Tony Szamboti]

"they demo'd an internal column to make sure the EPH didn't 'fly off' the top of the building, or cause the building to topple". [As if the terrorists of 9/11 were the slightest bit concerned about minimizing collateral damage, instead of maximizing it.]

So now you are saying the terrorists of 911 had something to do with the planning for WTC 7's demise concerning how the east penthouse fell.

I would agree that the planners were terrorists, and we know it couldn't have been nineteen muslim hijackers who planned the demolition of WTC 7.

I was getting ready to say you were behaving like a blowhard again, as you have been spouting a lot of unsupported nonsense again, but then I saw the above and had to say you must know deep down what went on and maybe had a Freudian slip.

 

[Tony Szamboti]

do you think there is any way to get the data from their "surveying instruments"?? i wonder what it would show? maybe from a foia but how would i go about that considering its the fire dept that made the measurements.
Peter Hayden:
“We had our special operations people set up surveying instruments to monitor, and see if there was any movement of, [WTC 7]. We were concerned of the possibility of collapse of the building. And we had a discussion with one particular engineer there, and we asked him, if we allowed it to burn could we anticipate a collapse, and if so, how soon?” The engineer apparently predicts correctly that WTC 7 will collapse and also the time it will take before it comes down. As Hayden will continue: “And it turned out that he was pretty much right on the money, that he said, ‘In its current state, you have about five hours.’” Hayden will not reveal the name of this engineer.

Good thought, but I doubt there was any data recorded and kept. It is incredible that people like Peter Hayden haven't been forced to reveal this mystery engineer's name under oath.

I get a kick out of apologist's who try to use "the bulge" as a reason for the building coming down. It is incredible that they would consider that even if there was a bulge in a wall on one side of a football field size building, that it would have any basis for explaining the complete symmetric freefall collapse for over 100 feet of that building.

 

[DGM]

It is incredible that people like Peter Hayden haven't been forced to reveal this mystery engineer's name under oath.

On what grounds would they force him (them) to do so? There has never been a crime connected with this.

Maybe you should work on getting this to court first.

 

[Tony Szamboti]

On what grounds would they force him (them) to do so? There has never been a crime connected with this.

Maybe you should work on getting this to court first.

It should have been a part of any real investigation into the unprecedented collapse of WTC 7 to talk to someone who had predicted it five hours beforehand.

How would this mystery engineer have been able to predict a natural collapse when the NIST natural collapse story says the circumstances didn't come together for the collapse until minutes before its occurrence?

Anyone who supports the present NIST story should be wondering how this guy knew five hours beforehand.

 

[DGM]

It should have been a part of any real investigation into the unprecedented collapse of WTC 7 if someone had predicted it five hours beforehand.

Why forced under oath? Is this guy a suspect?

How would this mystery engineer have been able to predict the collapse when the present official natural collapse story of NIST's says the circumstances didn't come together for the collapse until minutes before its occurrence?

Anyone who supports the present NIST story should be wondering how this guy knew five hours beforehand?

Did he actually predict the circumstances or did he just give an educated guess? In the context of that day, I think he was most likely going on the side of caution, considering two other buildings had already fallen.

 

[Tony Szamboti]

Why forced under oath? Is this guy a suspect?

Okay, I would settle for Peter Hayden and this mystery engineer being interviewed to hear what they have to say. You should agree that we need to know how he guessed so well.

Did he actually predict the circumstances or did he just give an educated guess? In the context of that day, I think he was most likely going on the side of caution, considering two other buildings had already fallen.

It would have been a spectacular guess given that NIST, by their own admission, had an extraordinarily hard time getting their arms around how WTC 7 could have collapsed in a natural way.

You can think whatever you want but this is a controversial issue and saying the building was going to collapse in five hours and being accurate about it smacks of more than erring on the side of caution.

 

[DGM]

You can think whatever you want but this is a controversial issue and saying the building was going to collapse in five hours and being accurate about it smacks of more than erring on the side of caution.

I hate to tell you this but, WTC7 is not a "controversial issue". Outside of a very small group of people it is not an issue at all. It certainly is not in the structural engineering or building world.

 

[Myriad]

It should have been a part of any real investigation into the unprecedented collapse of WTC 7 to talk to someone who had predicted it five hours beforehand.

How would this mystery engineer have been able to predict a natural collapse when the NIST natural collapse story says the circumstances didn't come together for the collapse until minutes before its occurrence?

Anyone who supports the present NIST story should be wondering how this guy knew five hours beforehand.

All the relevant circumstances came together long before "five hours beforehand." Those circumstances were: the building being empty, fires burning in the building, damage to the building exterior, the lack of water supply and manpower (due to higher priority demands on both) to fight the fire, the physical properties of the building's materials, and the design of the building.

NIST's task was to examine the contribution of the latter circumstance in the building's ultimate performance. They did that. The engineer on the scene might not have known the building's design in detail, but had additional information with which to estimate the time to failure: the ongoing progress of the fire insofar as externally observable, and the ongoing magnitude and trends of the observed leans and bulges. He or she called it admirably well, and that perceptive and accurate assessment might have saved numerous lives.

Respectfully,
Myriad

 

[Tony Szamboti]

I hate to tell you this but, WTC7 is not a "controversial issue". Outside of a very small group of people it is not an issue at all. It certainly is not in the structural engineering or building world.

It is to anyone I know with any technical background who has looked at it, is told NIST admits it was in free fall acceleration for 8 stories, but that the present U.S. government explanation is that it came down due to fire.

 

[Tony Szamboti]

All the relevant circumstances came together long before "five hours beforehand." Those circumstances were: the building being empty, fires burning in the building, damage to the building exterior, the lack of water supply and manpower (due to higher priority demands on both) to fight the fire, the physical properties of the building's materials, and the design of the building.

NIST's task was to examine the contribution of the latter circumstance in the building's ultimate performance. They did that. The engineer on the scene might not have known the building's design in detail, but had additional information with which to estimate the time to failure: the ongoing progress of the fire insofar as externally observable, and the ongoing magnitude and trends of the observed leans and bulges. He or she called it admirably well, and that perceptive and accurate assessment might have saved numerous lives.

Respectfully,
Myriad

Blah, blah, blah. Give us a break from this kind of ninny nonsense.

The NIST report clearly implies the circumstances specific to the way they claim the collapse occurred came together in the minutes before the collapse. That is unless you think the girder walk-off and buckling of column 79 were happening for hours beforehand.

 

[twinstead]

It is to anyone I know with any technical background who has looked at it, is told NIST admits it was in free fall acceleration for 8 stories, but that the present U.S. government explanation is that it came down due to fire.

The "US government explanation"? Seriously? Like the world's engineering and scientific communities where just told what to think by the government no questions asked?